1. Field of the Invention
The invention relates to automatically movable sliding doors and more particularly to a safety system for the controlled operation thereof and constitutes a distinct improvement over U.S. application Ser. No. 07/038,957 assigned to the same assignee as this application.
2. State of the Prior Art
Although automatic operation of sliding doors is well known as generally represented by U.S. Pat. Nos. 4009476, 40291176, 4621452, and 4706227, British Pat. No. 1418106 and West Germany Pat. No. 3202784, none of the inventions covered thereby approach the developments covered hereby. The present invention is distinctive from the prior art in that it includes safety means operable to control object presence detecting beams by the opening or closing movement of the door or doors with the beams projected in the threshold of the doorway and having a portion of each beam extending a predetermined distance on each side of the doorway. The improvement herein over U.S. application Ser. No. 07/038,987 resides in the utilization of computer means for the fast and consecutive operation of beam emitting transducers in the opening and closing of the door or doors.